The invention pertains to the driving of an electrochromic device from one transmissivity to another in the shortest amount of time but protecting from damage due to over-voltage. Particularly, it pertains to the magnitude and shape of the driving voltages of the device in view of its temperature.
There is a need for driving the electrochromic device to a selected transmissivity as fast as possible without damage to the device due to excessive driving voltages. The maximum magnitude of the driving voltages is dependent upon the temperature of the device. However, determination of the temperature is problematic since use of an external and/or specific temperature sensor is costly, difficult to manufacture and prone to failure.
Electrochromic technologies, specifically inorganic thin film materials, can result in a dimmable window controllable with a low voltage DC source. The glass is essentially a two terminal device which behaves similar to a battery. Applying a voltage to the device can move ions into the electrochromic layer where they will absorb light and dim or “color” the device. The ions can be moved back to the storage layer by reversing the applied voltage and cause the device to lighten or “bleach”.